Radio communication system, terminal device, base station device, radio communication method, and integrated circuit

ABSTRACT

A measurement object of which a terminal device takes a measurement is selected based on information of whether or not the measurement object included in a measurement configuration message notified by a base station device includes a parameter for a gap configuration or for a cell identification time configuration for small-cell measurement, and receiving power of a cell in which the terminal device itself is present.

TECHNICAL FIELD

The present invention relates to a radio communication system, aterminal device, a base station device, a radio communication method,and an integrated circuit, and more specifically relates to a radiocommunication system in which a small cell is arranged at a frequencydifferent from that of a macro cell, a terminal device, a base stationdevice, a radio communication method and an integrated circuit in theaforementioned radio communication system.

The present application claims priority based on Japanese PatentApplication No. 2013-012735 filed in Japan on Jan. 28, 2013, the contentof which is incorporated herein by reference.

BACKGROUND ART

In 3GPP (3rd Generation Partnership Project), a W-CDMA scheme has beenstandardized as a third-generation cellular mobile communication scheme,and service has been sequentially started. HSDPA with highercommunication speed has also been standardized and service has beencarried out.

On the other hand, in the 3GPP, evolution of third generation radioaccess (Evolved Universal Terrestrial Radio Access; hereinafter referredto as “EUTRA”) has also been standardized, and service has been started.As a downlink communication scheme of the EUTRA, an OFDM (OrthogonalFrequency Division Multiplexing) scheme which is resistant to multipathinterference and suitable for high-speed transmission has been employed.Moreover, a DFT (Discrete Fourier Transform)-spread OFDM scheme ofsingle carrier frequency division multiple scheme SC-FDMA (SingleCarrier-Frequency Division Multiple Access) capable of reducing a peakto average power ratio PAPR of a transmitted signal has been employed asan uplink communication scheme in consideration of cost and powerconsumption of a terminal device.

Further, in the 3GPP, working for standardizing Advanced-EUTRA, which isa further evolution from the EUTRA, is being carried out. It is assumedin the Advanced-EUTRA to use a band of up to 100-MHz bandwidth in eachof uplink and downlink to perform communications with transmission ratesof up to 1 Gbps or more in the downlink and 500 Mbps or more in theuplink.

In the Advanced-EUTRA, Heterogeneous Network (hereinafter, referred toas HetNet) is being considered in order to efficiently supportcommunication traffic which is generated locally. The HetNet is ahierarchical network in which, in addition to a conventional macro cell,a small cell such as a pico cell or a femto cell is arranged so as tohave a cell area overlapped with that of the macro cell (at a samefrequency or a different frequency), which allows dispersion ofcommunication traffic by mobile communication of a terminal device nearthe small cell which is present in the macro cell to the aforementionedsmall cell. Therefore, a mechanism by which a small cell is able to bedetected efficiently by a terminal device which is present in a macrocell is being considered in the 3GPP (NPL 1).

CITATION LIST Non-Patent Document

-   NPL 1: 3GPP TR (Technical Report) 36.839, V11.1.0, Evolved Universal    Terrestrial Radio Access (E-UTRA); Mobility enhancements in    heterogeneous networks-   NPL 2: R2-130451, Nokia Siemens Networks, Nokia Corporation,    “Background inter-frequency measurement for small cell discovery”,    3GPP TSG-RAN WG2#81, Malta, 28 Jan.-1 Feb. 2013-   NPL 3: 3GPP TS (Technical Specification) 36.331, V11.2.0, Evolved    Universal Terrestrial Radio Access (E-UTRA); Radio Resource Control    (RRC); Protocol specification

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

A mechanism for searching for a cell of a different frequency to takemeasurement exists under present conditions, which is a mechanismoptimized for searching for a cell of a handover destination by aterminal device when quality of a serving cell becomes worse (in a gapperiod configured by a base station device). Therefore, when a cell of adifferent frequency is searched for at all times in a state wherequality of the serving cell is not bad, power of the terminal device isconsumed significantly. NPL 2 proposes to introduce a new configurationvalue for detecting a small cell to a measurement gap configuration(MeasGapConfig) which is used for conventional measurement, but when aparameter for detecting a small cell is applied, there is influence onhandover characteristic when quality of the serving cell becomes worseas described above.

The present invention has been made in view of the aforementioned point,and on object thereof is to provide a radio communication system, aterminal device, a base station device, a radio communication method andan integrated circuit capable of searching for a cell of a differentfrequency efficiently.

Means for Solving the Problems

(1) In order to achieve the aforementioned object, the present inventiontakes the following means. That is, a radio communication system in anembodiment of the present invention is a radio communication system inwhich a base station device and a terminal device perform communication,in which the base station device includes means for notifying theterminal device of a measurement configuration message that includes ameasurement object indicating information such as a frequency to bemeasured, a configuration indicating a first gap period during whichcommunication with the terminal device is not performed temporarily, anda parameter for configuring a second gap period to the measurementobject, and the terminal device includes means for, in a case where theparameter for configuring the second gap period is included in ameasurement object of a different frequency notified from the basestation device, configuring the second gap period based on the first gapperiod and carrying out measurement of the different frequency in thesecond gap period.

(2) Moreover, a radio communication system in an embodiment of thepresent invention is a radio communication system in which a basestation device and a terminal device perform communication, in which thebase station device includes means for notifying the terminal device ofa measurement configuration message that includes a measurement objectindicating information such as a frequency to be measured, and theterminal device includes means for, in a case where a parameter for acell identification time configuration is not included in themeasurement object notified from the base station device, applying agiven cell identification time configuration to measurement of themeasurement object, and in a case where the parameter for the cellidentification time configuration is included in the measurement object,applying the cell identification time configuration based on theparameter for the cell identification time configuration, and means forperforming estimation of a mobility state of an own device, and in acase where a result of the estimation is higher speed than a given stateor in a case where receiving power of a serving cell in which the owndevice is present is less than a threshold notified from the basestation device, not carrying out measurement of the measurement objectin which the parameter for the cell identification time configuration isincluded.

(3) Moreover, a terminal device in an embodiment of the presentinvention is a terminal device that communicates with a base stationdevice, in which the terminal device includes means for receiving, fromthe base station device, a measurement configuration message thatincludes a measurement object indicating information such as a frequencyto be measured, a configuration indicating a first gap period duringwhich communication with the terminal device is not performedtemporarily, and a parameter for configuring a second gap period to themeasurement object, and means for, in a case where the parameter forconfiguring the second gap period is included in a measurement object ofa different frequency notified from the base station device, configuringthe second gap period based on the first gap period.

(4) Moreover, in the terminal device in the embodiment of the presentinvention, the terminal device performs estimation of a mobility stateof an own device, and in a case where a result of the estimation ishigher speed than a given state or in a case where receiving power of aserving cell in which the own device is present is less than a thresholdnotified from the base station device, does not carry out measurement ofthe different frequency in the second gap period.

(5) Moreover, a terminal device in an embodiment of the presentinvention is a terminal device that communicates with a base stationdevice, in which the terminal device includes means for receiving, fromthe base station device, a measurement configuration message thatincludes a measurement object indicating information such as a frequencyto be measured, and in a case where a parameter for a cellidentification time configuration is not included in the measurementobject notified from the base station device, applying a given cellidentification time configuration to measurement of the measurementobject, and in a case where the parameter for the cell identificationtime configuration is included in the measurement object, applying thecell identification time configuration based on the parameter for thecell identification time configuration.

(6) Moreover, in the terminal device in the embodiment of the presentinvention, the terminal device performs estimation of a mobility stateof an own device, and in a case where a result of the estimation ishigher speed than a given state or in a case where receiving power of aserving cell in which the own device is present is less than a thresholdnotified from the base station device, does not carry out measurement ofthe measurement object in which the parameter for the cellidentification time configuration is included.

(7) Moreover, a base station device in an embodiment of the presentinvention is a base station device that communicates with a terminaldevice, in which the base station device includes means for notifyingthe terminal device of a measurement configuration message that includesa measurement object indicating information such as a frequency to bemeasured, a configuration indicating a first gap period during whichcommunication with the terminal device is not performed temporarily, anda parameter for configuring a second gap period which is configured by apart of the first gap period to the measurement object.

(8) Moreover, a radio communication method in an embodiment of thepresent invention is a radio communication method applied to a radiocommunication system in which a base station device and a terminaldevice perform communication, including a step in which the base stationdevice notifies the terminal device of a measurement configurationmessage that includes a measurement object indicating information suchas a frequency to be measured, a configuration indicating a first gapperiod during which communication with the terminal device is notperformed temporarily, and a parameter for configuring a second gapperiod to the measurement object, and a step in which the terminaldevice, in a case where the parameter for configuring the second gapperiod is included in a measurement object of a different frequencynotified from the base station device, configures the second gap periodbased on the first gap period and carries out measurement of thedifferent frequency in the second gap period.

(9) Moreover, a radio communication method in an embodiment of thepresent invention is a radio communication method applied to a radiocommunication system in which a base station device and a terminaldevice perform communication, in which the base station device includesmeans for notifying the terminal device of a measurement configurationmessage that includes a measurement object indicating information suchas a frequency to be measured, and the method comprising a step in whichthe terminal device, in a case where a parameter for a cellidentification time configuration is not included in the measurementobject notified from the base station device, applies a given cellidentification time configuration to measurement of the measurementobject, and in a case where the parameter for the cell identificationtime configuration is included in the measurement object, applies thecell identification time configuration based on the parameter for thecell identification time configuration, and a step in which the terminaldevice further performs estimation of a mobility state of an own device,and in a case where a result of the estimation is higher speed than agiven state or in a case where receiving power of a serving cell inwhich the own device is present is less than a threshold notified fromthe base station device, does not carry out measurement of themeasurement object in which the parameter for the cell identificationtime configuration is included.

(10) Moreover, an integrated circuit in an embodiment of the presentinvention is an integrated circuit mounted in a terminal device thatcommunicates with a base station device, in which the integrated circuitcauses the terminal device to exert a function of receiving, from thebase station device, a measurement configuration message that includes ameasurement object indicating information such as a frequency to bemeasured, a configuration indicating a first gap period during whichcommunication with the terminal device is not performed temporarily, anda parameter for configuring a second gap period to the measurementobject, and a function of, in a case where the parameter for configuringthe second gap period is included in a measurement object of a differentfrequency notified from the base station device, configuring the secondgap period based on the first gap period.

(11) Moreover, an integrated circuit in an embodiment of the presentinvention is an integrated circuit mounted in a terminal device in aradio communication system in which a base station device and theterminal device perform communication, in which the integrated circuitcauses the terminal device to exert a function of receiving, from thebase station device, a measurement configuration message that includes ameasurement object indicating information such as a frequency to bemeasured, and a function of, in a case where a parameter for a cellidentification time configuration is not included in the measurementobject notified from the base station device, applying a given cellidentification time configuration to measurement of the measurementobject, and in a case where the parameter for the cell identificationtime configuration is included in the measurement object, applying thecell identification time configuration based on the parameter for thecell identification time configuration.

Effects of the Invention

As described above, according to embodiments of the present invention,it is possible to provide a radio communication system, a terminaldevice, a base station device, a radio communication method and anintegrated circuit capable of searching for a cell of a differentfrequency efficiently.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing one example of a base station deviceaccording to an embodiment of the present invention.

FIG. 2 is a block diagram showing one example of a terminal deviceaccording to the embodiment of the present invention.

FIG. 3 is a view showing a user plane architecture of the base stationdevice and the terminal device according to the embodiment of thepresent invention.

FIG. 4 is a view showing a control plane architecture of the basestation device and the terminal device according to the embodiment ofthe present invention.

FIG. 5 is a view showing one example of a measurement configuration in afirst embodiment of the present invention.

FIG. 6 is a block diagram showing one example of a measurement portionof a terminal device in the first embodiment of the present invention.

FIG. 7 is a flowchart showing one example of measurement procedure ofthe terminal device 2 in the first embodiment of the present invention.

FIG. 8 is a view showing one example of changing of ameasurement-gap-related parameter by using a measurement gap coefficientn in the first embodiment of the present invention.

FIG. 9 is a view showing another example of changing of themeasurement-gap-related parameter by using the measurement gapcoefficient n in the first embodiment of the present invention.

FIG. 10 is a flowchart showing one example of operation of configuring agap period to stop signal transmission to the terminal device 2 by abase station device 1 in the first embodiment of the present invention.

FIG. 11 is a view showing one example of a measurement configuration ina second embodiment of the present invention.

FIG. 12 is a block diagram showing one example of a measurement portionof a terminal device in the second embodiment of the present invention.

FIG. 13 is a flowchart showing one example of measurement procedure ofthe terminal device 2 in the second embodiment of the present invention.

FIG. 14 is a sequence chart showing one example of a conventional RRMmeasurement configuration management procedure.

FIG. 15 is a view showing one example of a conventional RRM measurementconfiguration.

MODE FOR CARRYING OUT THE INVENTION

Description will be given briefly for technologies involved in eachembodiment of the present invention before giving description for eachembodiment of the present invention.

[Physical Channel]

Description will be given for a main physical channel (or physicalsignal) used for EUTRA and Advanced EUTRA. A channel means a medium usedfor signal transmission, and a physical channel means a physical mediumused for signal transmission. There is a possibility that in the EUTRAand the advanced EUTRA, the physical channel is added or a structure ora format style thereof is modified or added in the future, but, even inthe case of modification or addition, there is no influence ondescription of each embodiment of the present invention.

In the EUTRA and the Advanced EUTRA, scheduling of the physical channelis managed by using a radio frame. One radio frame is 10 ms and oneradio frame is configured by ten subframes. Further, one subframe isconfigured by two slots (that is, one slot has 0.5 ms). Moreover,management is performed by using a resource block as a minimum unit ofscheduling, in which physical channels are arranged. The resource blockis defined as a fixed frequency region in which a frequency axis isconfigured by an assembly of a plurality of subcarriers (for example,twelve subcarriers) and a region configured by a fixed transmission timeinterval (one slot).

Synchronization signals are configured by three types of primarysynchronization signals and secondary synchronization signals which areconfigured by 31 types of codes which are arranged alternately in afrequency region, and a combination of signals of the primarysynchronization signals and the secondary synchronization signalsindicates 504 cell identifiers (physical cell ID (Physical CellIdentity; PCI)) that identify a base station device and a frame timingfor radio synchronization. A terminal device specifies a cell ID ofsynchronization signals received by cell search.

A physical broadcast channel (PBCH) is transmitted for the purpose ofnotifying a control parameter (broadcast information or systeminformation) which is commonly used in terminal devices in a cell.Regarding broadcast information which is not notified by the physicalbroadcast channel, a radio resource is notified by a physical downlinkcontrol channel and is transmitted with a layer 3 message (systeminformation) by a physical downlink shared channel. As the broadcastinformation, a cell global identifier (CGI) indicating an identifier ofan individual cell, a tracking area identifier (TAI) for managing astandby area by paging, random access configuration information (such asa transmission timing timer), shared radio resource configurationinformation, or the like is notified.

Downlink reference signals are classified into a plurality of typesdepending on intended use thereof. For example, cell-specific referencesignals (CRSs) are pilot signals which are transmitted withpredetermined power for each cell, and are downlink reference signalswhich are iterated periodically in a frequency region and a time regionbased on a predetermined rule. The terminal device measures receptionquality for each cell by receiving the cell-specific reference signals.Moreover, the terminal device uses the downlink cell-specific referencesignals also as reference signals for demodulation of the physicaldownlink control channel or the physical downlink shared channel that istransmitted at the same time with the cell-specific reference signals.As a sequence used for the cell-specific reference signals, a sequencewhich is identifiable for each cell is used.

Further, the downlink reference signals are used also for estimation ofchannel fluctuation of the downlink. The downlink reference signals usedfor estimation of channel fluctuation are referred to as channel stateinformation reference signals (CSI-RSs) or CSI reference signals.Moreover, the downlink reference signals which are configuredindividually for each terminal device are referred to as UE specificreference signals (URSs) or dedicated RSs (DRSs), and used fordemodulation of the physical downlink control channel or the physicaldownlink shared channel.

The physical downlink control channel (PDCCH) is transmitted as severalOFDM symbols from beginning of each subframe, and is used for thepurpose of giving instruction of radio resource allocation informationin accordance with scheduling of a base station device and an adjustmentamount of increase and decrease in transmission power to the terminaldevice. The terminal device needs to acquire radio resource allocationinformation called uplink grant in the case of transmission and downlinkgrant (downlink assignment) in the case of reception from the physicaldownlink control channel by monitoring the physical downlink controlchannel addressed to the own device before transmitting and receiving alayer 3 message (paging, hand-over command, and the like) that isdownlink data or downlink control data, and by receiving the physicaldownlink control channel addressed to the own device. Note that, thephysical downlink control channel is also able to be configured so as tobe, other than to be transmitted as the ODFM symbols described above,transmitted in a region of a resource block allocated from the basestation device to the terminal device in an individual (dedicated)manner.

A physical uplink control channel (PUCCH) is used for performing areception confirmation response (Acknowledgement/NegativeAcknowledgement; ACK/NACK) of data transmitted on the physical downlinkshared channel, notification of channel information (channel stateinformation) of the downlink, and a scheduling request (SR) which is aradio resource allocation request (radio resource request) of theuplink. The channel state information (CSI) includes CQI (ChannelQuality Indicator), PMI (Precoding Matrix Indicator), PTI (PrecodingType Indicator), and RI (Rank Indicator). Each indicator is representedas indication in some cases, but intended use and meaning thereof aresame.

The physical downlink shared channel (PDSCH) is used also for notifyingthe terminal device of broadcast information (system information) whichis not notified by paging or the physical broadcast channel in additionto downlink data as the layer 3 message. Radio resource allocationinformation of the physical downlink shared channel is indicated by thephysical downlink control channel.

A physical uplink shared channel (PUSCH) mainly transmits uplink dataand uplink control data, and is also able to include reception qualityof the downlink and control data such as ACK/NACK. Moreover, it is usedfor notifying the base station device of the uplink control informationin addition to the uplink data as the layer 3 message. Further, in thesame manner as the case of the downlink, radio resource allocationinformation of the physical uplink shared channel is indicated on thephysical downlink control channel.

An uplink reference signal (also referred to as an uplink pilot signalor an uplink pilot channel) includes a demodulation reference signal(DMRS) which is used by the base station device for demodulating thephysical uplink control channel PUCCH and/or the physical uplink sharedchannel PUSCH, and a sounding reference signal (SRS) which is used bythe base station device mainly for estimating the channel state of theuplink. Moreover, as the sounding reference signal, there are a periodicsounding reference signal (Periodic SRS) and an aperiodic soundingreference signal (Aperiodic SRS).

A physical random access channel (PRACH) is a channel which is used fornotifying a preamble sequence and has a guard time. The preamblesequence is configured so as to indicate 6-bit information by preparingsixty four types of sequences. The physical random access channel isused as access means to the base station device from the terminaldevice. The terminal device uses the physical random access channel formaking a radio resource request when the physical uplink control channelis not configured, or requesting transmission timing adjustmentinformation (also called timing advance; TA) which is required foraligning an uplink transmission timing to a reception timing window ofthe base station device to the base station device.

Specifically, the terminal device transmits the preamble sequence byusing the radio resource for the physical random access channel that isconfigured by the base station device. The terminal device which hasreceived the transmission timing adjustment information configures atransmission timing timer for counting an effective time of thetransmission timing adjustment information which is configured commonlyby broadcast information (or configured individually by the layer 3message) to manage an uplink state as a transmission timing adjustedstate during an effective time of the transmission timing timer (duringcounting) and as a transmission timing non-adjusted state (transmissiontiming un-adjusted state) other than the effective period (duringstopping). The layer 3 message is a message of control plane which isexchanged between RRC (radio resource control) layers of the terminaldevice and the base station device, and is used synonymously with RRCsignaling or an RRC message. Note that, since physical channels otherthan above are not concerned with each embodiment of the presentinvention, detailed description thereof will be omitted.

[Measurement]

FIG. 14 is a sequence chart for explaining a radio resource management(RRM) measurement configuration management method of a terminal device 2and a base station device 1 in EUTRA.

In an example of FIG. 14, the base station device 1 is able to use twodifferent frequencies of F1 and F2 as frequencies handled by the ownstation, and the terminal device 2 and the base station device 1 are ina state where radio connection is established (radio resource controlconnected (RRC_Connected)) at the frequency F1. Here, the base stationdevice 1 transmits a message including a measurement configuration(hereinafter, referred to as a measurement configuration message) formeasuring reception quality of a cell in communication (serving cell)and other cell (neighboring cell) to the terminal device 2 (step S141).The measurement configuration message includes at least one measurementconfiguration information for each of the frequencies to be measured(frequency F1 and frequency F2). The measurement configurationinformation is configured by a measurement ID, a measurement object, ameasurement object ID corresponding to the measurement object, a reportconfiguration including a measurement event, and a report configurationID corresponding to the report configuration. It may be configured sothat a plurality of report configuration IDs are linked to onemeasurement object ID. In the same manner, it may be configured so thatone report configuration ID is linked to a plurality of measurementobject IDs.

Moreover, the measurement configuration message is also able to includea measurement gap configuration (measGapConfig) and a threshold calleds-Measure.

The measurement gap configuration is such that in order for the terminaldevice 2 to measure a cell of a different frequency or a neighboringcell of a different radio communication technology system, the basestation device 1 configures a period during which transmission to theterminal device 2 is not performed in a serving cell (gap period) tonotify the terminal device 2, and thereby, the terminal device 2 is ableto measure a neighboring cell of the different frequency and aneighboring cell of the different radio communication technology systemby interrupting reception operation at the serving cell. In thismeasurement gap configuration, parameters of a gap pattern identifier(gp0 or gp1) and a value of the gap pattern identifier (gap offset) arenotified. A measurement gap length (MGL), a measurement gap repetitiveperiod (MGRP) and a minimum measurement time during a period of 480 ms(Tinter1) are decided based on the notified gap pattern identifier, anda start timing of the measurement gap is decided based on the notifiedgap offset. The aforementioned MGL, MGRP, Tinter1 and gap offset arecollectively referred to as a measurement-gap-related parameter in thepresent application. Further, one measurement gap configuration is ableto be configured to the terminal device 2, and the terminal device 2takes measurement for all of different frequencies and different radiocommunication technology systems by using this gap period. Moreover, atime for detecting and measuring a cell is regulated based on themeasurement gap configuration, the number of different frequencies of ameasurement object, a type of a radio communication technology, andother configuration, and the terminal device 2 needs to performdetection and measurement of the cell within this regulated time. Forexample, when discontinuous reception (DRX) is not configured in afrequency division duplex (FDD) system, the terminal device 2 whichtakes measurement with Nfreq pieces of different frequencies needs to beable to detect a cell of the EUTRA that exists at each frequency withinTidentify_inter=480×480÷Tinter1×Nfreq [ms].

The s-Measure is a parameter for configuring so as to take neighboringcell measurement when receiving power of a serving cell is less than athreshold (s-Measure), and is able to prevent unnecessary neighboringcell measurement for handover when communication quality of the servingcell is good. One s-Measure is able to be configured for the terminaldevice 2, and when it is configured t to 0 or when it is not configured,the terminal device 2 takes measurement which is configured at all timesregardless of quality of the serving cell.

Next, description will be given for a measurement configuration messageby taking a specific example. Here, description will be given by usingFIG. 15 for a case where two measurement objects (frequency F1 andfrequency F2) and three report configurations are notified and threemeasurement IDs are configured to combinations of the aforementionedmeasurement objects and report configurations.

The base station device 1 allocates identifiers 0 and 1 as measurementobject IDs to the frequencies F1 and F2 as the measurement objects,respectively, to notify the terminal device 2. Moreover, the basestation device 1 allocates identifiers 0, 1 and 2 as reportconfiguration IDs to a report configuration 1, a report configuration 2and a report configuration 3 as the report configurations, respectively,to notify the terminal device 2. Further, the base station device 1notifies the terminal device 2 of the measurement IDs which areassociated with (linked to) combinations of the aforementionedidentifiers of the measurement objects and the aforementionedidentifiers of the report configurations. Further, the base stationdevice 1 notifies the terminal device 2 of measurement gapconfiguration, s-Measure or the like as necessary.

In FIG. 15, as a measurement ID #0, a combination of the measurementobject of the identifier 0 (frequency F1) and the report configurationof the identifier 0 is specified. In the same manner, a combination ofthe measurement object of the identifier 0 (frequency F1) and the reportconfiguration of the identifier 1 is specified to a measurement ID #1,and a combination of the measurement object of the identifier 1(frequency F2) and the report configuration of the identifier 2 isspecified to a measurement ID #2.

Moreover, the measurement event information is information configured bymeasurement events indicating conditions, for example, including whenreception quality of a cell-specific reference signal of a serving cellis less than/more than a predetermined threshold, when reception qualityof a cell-specific reference signal of a neighboring cell is less thanthat of the serving cell, and when reception quality of the neighboringcell is more than a predetermined threshold, and parameters used fordetermining these conditions. For the parameters, information such as athreshold, an offset value, a time required to establish a measurementevent and the like are configured. In NPL 3, for example, as ameasurement event A1, it is defined to make a report when receptionquality of a serving cell becomes more excellent than a threshold.Moreover, as a measurement event A3, it is defined to make a report whenreception quality of a neighboring cell becomes more excellent than oneobtained by adding an offset value to the reception quality of theserving cell. Further, as a measurement event A4, it is defined to makea report when the reception quality of the neighboring cell becomes moreexcellent than a threshold.

The terminal device 2 saves the measurement configuration information,which is configured from the base station device 1, as internalinformation at step S142. When the measurement configuration informationwas able to be configured without error, the terminal device 2 thentransmits a message indicating completion of a measurement configuration(measurement configuration completion message) to the base stationdevice 1 at step S143. The terminal device 2 performs management byassociating the measurement ID, the measurement object ID and the reportconfiguration ID so as to be linked in one as described above and startsmeasurement based on measurement information corresponding to each ID.When these three IDs are linked in one, related measurement is startedby regarding as effective, and when these three IDs are not linked inone (when any of the IDs is not configured), the related measurement isnot started by regarding as ineffective. When measurement of a differentfrequency or a different radio communication technology system isconfigured, the terminal device 2 takes measurement by using a gapperiod based on the measurement gap configuration. Moreover, in a casewhere the s-Measure is notified, the terminal device 2 may takemeasurement of the neighboring cell only when receiving power of theserving cell is less than the threshold (s-Measure).

In addition, when any of the measurement events which are configuredsatisfies condition in accordance with the parameter in the terminaldevice 2, this measurement event is set as being triggered and ameasurement report message is transmitted to the base station device 1(step S144). The measurement report message is reported with at leastthe measurement ID which is linked to the report configuration ID of themeasurement event which is triggered and a measurement result of arelated cell if necessary configured. Since the base station device 1grasps to which report configuration ID of the measurement event themeasurement ID is linked, the terminal device 2 does not need to notifythe report configuration ID with the measurement report message.

Description will hereinafter be given in detail for preferableembodiments of the present invention with reference to accompanyingdrawings while considering above matters. Note that, in the descriptionof the embodiments of the present invention, when specific descriptionof well-known functions or configurations related to the embodiments ofthe present invention may be considered as making the subject matter ofthe embodiments of the present invention unclear, the detaileddescription thereof will be omitted.

First Embodiment

Description will be given below for a first embodiment of the presentinvention.

FIG. 1 is a block diagram showing one example of a base station device 1according to the embodiment of the present invention. This base stationdevice 1 is configured by a reception portion 101, a demodulationportion 102, a decoding portion 103, a control portion 104, a codingportion 105, a modulation portion 106, a transmission portion 107, anetwork signal transmission and reception portion 108 and a higher layer109.

The higher layer 109 outputs downlink traffic data and downlink controldata to the coding portion 105. The coding portion 105 codes each datawhich is input to output to the modulation portion 106. The modulationportion 106 performs modulation of a signal input from the codingportion 105. Moreover, the signal modulated in the modulation portion106 is superimposed with a downlink reference signal and mapped as asignal of a frequency region. The transmission portion 107 converts thesignal input from the modulation portion 106 into a signal of a timeregion, and transmits the converted signal while carrying on a carrierwave of a given frequency to perform power amplification. A downlinkdata channel in which the downlink control data is arranged typicallyconfigures a layer 3 message (RRC (Radio Resource Control) message).

Moreover, the reception portion 101 converts a received signal from aterminal device 2 (refer to FIG. 2) into a base-band digital signal. Thedigital signal converted at the reception portion 101 is input to thedemodulation portion 102 and demodulated. The signal demodulated at thedemodulation portion 102 is subsequently input to the decoding portion103 and decoded. The decoding portion 103 appropriately separates thereceived signal into uplink traffic data and uplink control data andoutputs each of them to the higher layer 109.

Base station device control information needed for controlling each ofthese blocks is input to the control portion 104 by the higher layer109, and the control portion 104 appropriately inputs the base stationdevice control information related to transmission as transmissioncontrol information to each of the blocks of the coding portion 105, themodulation portion 106 and the transmission portion 107, and the basestation device control information related to reception as receptioncontrol information to each of the blocks of the reception portion 101,the demodulation portion 102 and the decoding portion 103.

On the other hand, the network signal transmission and reception portion108 performs transmission or reception of a control message between aplurality of base station devices 1 (or between a control station device(MME), a gateway device (Gateway), an MCE and the base station device1). The control message is transmitted or received via a network line.The control message is exchanged on a logical interface called an S1interface, an X2 interface, an M1 interface or an M2 interface. Othercomponents of the base station device 1 are not involved with thepresent embodiment and thus omitted in FIG. 1.

FIG. 2 is a block diagram showing one example of the terminal device 2according to the embodiment of the present invention. This terminaldevice 2 is configured by a reception portion 201, a demodulationportion 202, a decoding portion 203, a measurement portion 204, acontrol portion 205, a random access processing portion 206, a codingportion 207, a modulation portion 208, a transmission portion 209 and ahigher layer 210.

Prior to reception, the higher layer 210 outputs terminal device controlinformation to the control portion 205. The control portion 205appropriately outputs the terminal device control information related toreception as reception control information to the reception portion 201,the demodulation portion 202, the decoding portion 203 and themeasurement portion 204. The reception control information includesinformation of demodulation information, decoding information,information of a reception frequency band, a reception timing related toeach channel, a multiplexing method and radio resource arrangementinformation as reception schedule information as reception schedulinginformation.

The reception portion 201 receives a signal from the base station device1 described below through one or more not-shown receivers in a frequencyband which is notified with the reception control information, andconverts the received signal into a base-band digital signal to outputto the demodulation portion 202. Further, the reception portion 201outputs a received reference signal to the measurement portion 204. Thedemodulation portion 202 demodulates the received signal to output tothe decoding portion 203. The decoding portion 203 correctly decodes thedemodulated signal based on the reception control information,appropriately separates it into downlink traffic data and downlinkcontrol data, and outputs each of them to the higher layer 210. When ameasurement configuration message is included in the signal decoded atthe decoding portion 203, the higher layer 210 notifies the measurementportion 204 of measurement and report configuration specified with theaforementioned measurement configuration message. The measurementportion 204 measures RSRP. RSRQ and the like of the received referencesignal and outputs a measurement result thereof to the higher layer 210.

Moreover, prior to transmission, the higher layer 210 outputs terminaldevice control information to the control portion 205. The controlportion 205 appropriately outputs the terminal device controlinformation related to transmission as transmission control informationto the random access processing portion 206, the coding portion 207, themodulation portion 208 and the transmission portion 209. Thetransmission control information includes information of codinginformation, modulation information, information of a transmissionfrequency band, a transmission timing related to each channel, amultiplexing method and radio resource arrangement information as uplinkscheduling information of a transmitted signal.

The higher layer 210 appropriately outputs uplink traffic data anduplink control data to the coding portion 207 according to an uplinkchannel. In accordance with the transmission control information, thecoding portion 207 appropriately codes each data to output to themodulation portion 208. The modulation portion 208 performs modulationof a signal which is coded at the coding portion 207. Moreover, themodulation portion 208 multiplexes a downlink reference signal with themodulated signal, followed by mapping into a frequency band.

The transmission portion 209 converts the signal of the frequency band,which is output from the modulation portion 208, into a signal of a timeregion, and transmits the converted signal from one or more not-showntransmitters while carrying on a carrier wave of a given frequency toperform power amplification.

Other components of the terminal device 2 are not involved with thepresent embodiment and thus omitted in FIG. 2.

Next, an architecture of a radio interface protocol between the basestation device and the terminal device is shown. FIG. 3 is a blockdiagram showing a radio protocol architecture of a user plane (U-plane).Moreover, FIG. 4 is a block diagram showing a radio protocolarchitecture of a control plane (C-plane). The user plane is a protocolstack for transmitting and receiving user data, and the control plane isa protocol stack for transmitting and receiving a control signal.

In FIG. 3 and FIG. 4, in a physical layer (PHY) which is a firsthierarchy (layer 1), communication is performed between differentphysical hierarchies, that is, between the physical layers on atransmission side and a reception side by using the physical channeldescribed above. The physical layer is coupled to a higher medium accesscontrol (MAC) layer through a transport channel, and the physical layerperforms information transfer service to the MAC layer through thistransport channel.

In the MAC layer of a second hierarchy (layer 2), mapping of a logicalchannel and the transport channel, error correction by HARQ (HybridAutomatic Repeat reQuest), transfer processing based on priority betweenthe logical channels, and the like are performed. The MAC layer iscoupled to a radio link control (RLC) layer which is a higher hierarchythrough the logical channel.

The RLC layer of the second hierarchy supports reliability of datatransfer. There are three types of operation modes including atransparent mode (TM), an unacknowledged mode (UM) and an acknowledgedmode (AM) in the RLC layer according to a data transmission method. Inthe AM, error correction and protocol error detection by ARQ, etc., areperformed.

A PDCP (Packet Data Convergence Protocol) layer in the second hierarchyperforms header compression for reducing an IP packet header size, dataencryption, decryption of encrypted one and the like.

A radio resource control (RRC) layer in a third hierarchy (layer 3) isdefined only by the control plane. The RRC layer performs broadcastingof NAS (non-access stratum) or AS (access stratum) related information,management of RRC connection (establishment/maintenance/release),configuration, re-configuration and release of a radio bearer (RB),mobility (handover), management and reporting of measurement, Qosmanagement and the like.

The NAS layer positioned above the RRC layer performs sessionmanagement, mobility management and the like.

Here, the MAC layer and the RRC layer of the base station device 1 existas a part of the higher layer 109. Moreover, the MAC layer of theterminal device 2 exists as a part of the random access processingportion 206 and the higher layer 209, and the RRC layer of the terminaldevice 2 exists as a part of the measurement portion 204 and the higherlayer 209.

Next, description will be given for a measurement configuration in thepresent embodiment.

In the same manner as the conventional RRM measurement configurationdescribed above, the measurement configuration in the present embodimentis configured by a measurement ID, a measurement object, a measurementobject ID corresponding to the measurement object, a reportconfiguration including a measurement event, and a report configurationID corresponding to the report configuration. Further, it is defined inthe present embodiment so that a configuration of the measurement objectis able to include a gap configuration for small-cell measurement.

Here, in each embodiment of the present invention described below,measurement of a different frequency cell is classified into “ordinarymeasurement” and “small-cell measurement”, in which the “ordinarymeasurement” is conventional measurement mainly aiming to maintainconnection when receiving power of a serving cell is reduced or move toa frequency layer having higher priority or the like, and the“small-cell measurement” is to measure a cell of a different frequencymainly aiming offload. That is, it should be noted that the measurementof a small cell aiming to maintain connection is a target of the“ordinary measurement” of the present application and the measurement ofa small cell is not necessarily classified into the “small-cellmeasurement”.

An example that two measurement objects are defined as the measurementconfiguration is shown in FIG. 5. In the measurement configuration, areport configuration is included in addition to the measurement objectand a measurement ID is configured to a combination of theaforementioned measurement object and report configuration.

In FIG. 5, a combination of a measurement object (frequency F2) of anidentifier 0 and a report configuration 1 of an identifier 0 isspecified as a measurement ID #0. In the same manner, a combination of ameasurement object (frequency F3, gap configuration for small-cellmeasurement) of an identifier 1 and a report configuration 2 of anidentifier 1 is specified as a measurement ID #1. Moreover, it is sethere that the event A1 described above is specified as the measurementevent for the report configuration 1 and the event A3 described above isspecified as the measurement event for the report configuration 2.

Next, description will be given for the measurement portion 204 in thepresent embodiment by using FIG. 6.

The measurement portion 204 includes an RRC layer reference signalmeasurement portion 61 and a PHY layer reference signal measurementportion 62. The PHY layer reference signal measurement portion 62measures RSRP and RSRQ of a reference signal input from the receptionportion 201, a channel state and the like to notify the RRC layerreference signal measurement portion 61. The RRC layer reference signalmeasurement portion 61 averages, if necessary, individual measurementresults notified from the PHY layer reference signal measurement portion62 for the measurement object which is configured by the measurementconfiguration notified from the higher layer 210 to consider whether ornot to be matched with the report configuration, and notifies themeasurement results to the higher layer 210. Here, when a gapconfiguration for small-cell measurement is included in the measurementobject of the measurement configuration notified from the higher layer210, the measurement portion 204 considers that this measurement objectis the configuration for the small-cell measurement.

Here, the terminal device 2, when the gap configuration for small-cellmeasurement is included in the measurement object of the measurementconfiguration message notified from the base station device 1 asdescribed above, may consider that this measurement object is theconfiguration for small-cell measurement, or when information of one bitindicating small-cell measurement is included in the measurement object,may consider that this measurement object is the configuration forsmall-cell measurement. Alternatively, information of two bits or moremay be included in the measurement object to show that this measurementobject is the configuration for small-cell measurement, a configurationfor ordinary measurement, or a configuration for taking both ofsmall-cell measurement and ordinary measurement.

Further, the gap configuration for small-cell measurement is informationneeded for configuring a measurement-gap-related parameter for use insmall-cell measurement, and, for example, may be themeasurement-gap-related parameter for use in small-cell measurementitself (a part or all of MGL, MGRP, Tinter1, and gap offset), bitinformation indicating whether or not a measurement-gap-relatedparameter which is notified or prescribed in advance is applied to thecorresponding measurement object, or a measurement gap coefficient ndescribed below.

Subsequently, description will be given for one example of measurementprocedure of the terminal device 2 in a communication system of thepresent embodiment by using a flowchart of FIG. 7.

In FIG. 7, first, the terminal device 2 receives a measurementconfiguration message from the base station device 1, and, based onwhether or not the gap configuration for small-cell measurementdescribed above is included in a measurement object, determines whetheror not this measurement object is for use in small-cell measurement(step S71). When the measurement object is for use in small-cellmeasurement (Yes at step S71), a measurement-gap-related parameter ischanged to one for use in small-cell measurement (step S72), and theflow shifts to step S74. When the measurement object is for use inordinary measurement (No at step S71), a configuration is made so thatthe measurement-gap-related parameter which is configured based on a gapoffset notified from the base station device 1 is used as it is (stepS73), and the flow shifts to step S74. At step S74, the terminal device2 determines whether or not the aforementioned configuration is made forall measurement objects requiring a measurement gap, which areconfigured to the own device, and when there is a measurement object towhich the configuration is not made, the flow shifts to step S71 to makea configuration of a measurement-gap-related parameter of a nextmeasurement object. When the aforementioned configuration is made forall the measurement objects requiring a measurement gap, which areconfigured to the own device, at step S74, the flow shifts to step S75.The terminal device 2 measures receiving power of a serving cell inwhich the own device is present and makes comparison with a threshold(s-Measure) at step S75. When the receiving power of the serving cell isgreater than or equal to the threshold (Yes at step S75), measurement ofthe measurement object for use in small-cell measurement is carried out(step S76). When the receiving power of the serving cell is less thanthe threshold (No at step S75), measurement of the measurement objectfor use in ordinary measurement is carried out (step S77).

As described above, when information of whether or not to be for use insmall-cell measurement is included in the configuration of themeasurement object and the terminal device 2 switches small-cellmeasurement and ordinary measurement based on quality (receiving power)of the serving cell, it becomes possible to apply a configuration of themeasurement gap suitable for each measurement and to search for adifferent frequency cell efficiently.

Further, measurement of the measurement object for use in small-cellmeasurement may not be performed not only when the receiving power ofthe serving cell is less than the threshold but when a mobility stateestimation value (MSE) of the terminal device 2 exceeds a threshold (forexample, in the case of middle speed or more or in the case of highspeed when the estimation value is represented by low speed, middlespeed or high speed). That is, when small-cell measurement itself is notperformed when the terminal device 2, even if being connected to a smallcell, falls out of the cell immediately (at the time of high-speedmovement), it becomes possible to search for a different frequency cellefficiently. The aforementioned threshold of the mobility stateestimation value may be configured individually for each measurementobject, or may be common in all the measurement objects for use insmall-cell measurement. In a case where the threshold is configured foreach measurement object, for example, when a cell size of a small cellis different for each frequency, etc., by setting the threshold as “highspeed” at the frequency with a large cell size and setting the thresholdas “middle speed” at the frequency with a small cell size, it becomespossible to search for a different frequency cell efficiently accordingto the cell size handled at each frequency.

Moreover, in conventional measurement, when a measurement object is adifferent frequency, time for cell identification is specified inconsideration of the number of frequencies to be measured. However, whensmall-cell measurement and ordinary measurement are taken exclusively asdescribed above, if the measurement object for small-cell measurement isincluded in calculation of time for cell identification in ordinarymeasurement, a conventional requirement condition is not satisfied inordinary measurement. Therefore, when carrying out ordinary measurement,it is preferable that a frequency of small-cell measurement is notincluded in calculation of Tidentify_inter or the like (that is, afrequency of small-cell measurement is not included in Nfreq). Further,to the contrary, when carrying out small-cell measurement, it ispreferable that a frequency of ordinary measurement is not included incalculation of Tidentify_inter or the like (that is, frequency ofordinary measurement is not included in Nfreq). Here, when measurementof the frequency of small-cell measurement is configured also toordinary measurement, this frequency is preferably included in Nfreq ofboth of them.

Next, description will be given for a case where the measurement gapcoefficient n is notified as a gap configuration for small-cellmeasurement in the present embodiment.

This measurement gap coefficient n is used for changing a part of ameasurement-gap-related parameter. For example, as shown in FIG. 8, ameasurement gap repetitive period (MGRP) is multiplied by n to make sucha configuration that a period of a measurement gap becomes longer than aperiod for ordinary measurement. Further, a configuration may be made sothat time for cell identification (Tidentify_inter) becomes long bymultiplying Tinter1 by 1/n. In this manner, the terminal device 2 whichis notified of the measurement object including the measurement gapcoefficient n regards this measurement object as the measurement objectfor use in small-cell measurement and changes MGRP and Tidentify_interwhich are configured for ordinary measurement, so that power saving fordifferent frequency cell search aiming offload becomes possible.

Further, as another example, as shown in FIG. 9, a gap configurationdefined by MGL and MGRP may be made effective for a fixed period (Tgap)and a gap configuration may be made ineffective for a subsequent periodof Tgap x (n−1). In this manner, the terminal device 2 which is notifiedof the measurement object including the measurement gap coefficient nregards this measurement object as the measurement object for use insmall-cell measurement, and uses the measurement gap coefficient n toconfigure the period during which small-cell measurement using themeasurement-gap-related parameter which is determined based on themeasurement gap configuration (gp0 or gp1) notified for ordinarymeasurement is made effective and the period during which it is madeineffective, so that power saving for different frequency cell searchaiming offload becomes possible.

Moreover, the aforementioned measurement gap coefficient n may bechanged according to the mobility state estimation value of the terminaldevice 2. A changing method may be scaling by the mobility stateestimation value (performing weighting so that n becomes small as speedbecomes high) or may be notification of n (nHigh, nMid, nLow) for eachmobility state estimation value (for example, for each of high speed,middle speed and low speed). At this time, when n is 0, small-cellmeasurement for the corresponding measurement object may not beperformed. For example, by setting values of nHigh and nMid to 0, it ispossible to cause only the terminal device 2 which moves at low speed totake small-cell measurement, so that it becomes possible to search for adifferent frequency cell efficiently.

Though description has been given here for introduction of themeasurement gap coefficient n as a specific example, without limitationthereto, a configuration may be merely made so that a measurement gapused for small-cell measurement become different from a measurement gapused for ordinary measurement. At this time, it is preferable that a gapperiod which is configured for use in small-cell measurement (second gapperiod) is a part of a gap period which is configured for use inordinary measurement (first gap period). This is because when theterminal device 2 switches ordinary measurement and small-cellmeasurement based on receiving power of the serving cell, the basestation device 1 does not know a timing of this switching at theterminal device 2. Therefore, when a configuration is made so that thesecond gap period which is configured for use in small-cell measurementbecomes a part of the first gap period which is configured for use inordinary measurement and the base station device 1 stops signaltransmission to the terminal device 2 in the first gap period which isconfigured for use in ordinary measurement, it is possible to performcommunication in the serving cell regardless of the switching timing atthe terminal device 2.

Next, description will be given for one example of operation forconfiguring a gap period during which the base station device 1 stopssignal transmission to the terminal device 2 by using FIG. 10. Asdescribed above, when the terminal device 2 switches ordinarymeasurement and small-cell measurement based on the receiving power ofthe serving cell, the base station device 1 does not know a timing ofthis switching at the terminal device 2. Therefore, the base stationdevice 1 determines whether or not the measurement object which is in astate where measurement is effective (a state where a measurement ID, ameasurement object ID and a report configuration ID are linked in one)among measurement objects notified to the terminal device 2 includes adifferent frequency or a different radio communication technology system(step S1001). When the measurement object does not include a differentfrequency or a different radio communication technology system (No atstep S1001), a measurement gap is not configured. When the measurementobject includes a different frequency or a different radio communicationtechnology system (Yes at step S1001), the base station device 1determines whether or not the measurement object which is in a statewhere the aforementioned measurement is effective is only for aconfiguration for use in small-cell measurement (step S1002). When themeasurement object is only for a configuration for use in small-cellmeasurement (Yes at step S1002), the measurement gap is configured toone for use in small-cell measurement (step S1003). When the measurementobject includes other than the configuration for use in small-cellmeasurement (No at step S1002), the measurement gap is configured to onefor use in ordinary measurement (step S1004). The base station device 1which has configured the measurement gap performs scheduling ofcommunication with the terminal device 2 based on the configuredmeasurement gap. With operation above, even when the terminal device 2switches ordinary measurement and small-cell measurement based on thereceiving power of the serving cell, it is possible to performcommunication in the serving cell efficiently.

Note that, though an example is shown in the description above that ameasurement object for use in small-cell measurement is not measuredwhen the receiving power of the serving cell is less than s-Measure, themeasurement object for use in small-cell measurement may be measuredregardless of a value of s-Measure or even when s-Measure is notconfigured. In this case, the base station device 1 and the terminaldevice 2 need to manage the measurement gap for ordinary measurement andthe measurement gap for small-cell measurement independently. However,as described above, when a configuration is made so that the gap periodwhich is configured for use in small-cell measurement becomes a part ofthe gap period which is configured for use in ordinary measurement andthe base station device 1 stops signal transmission to the terminaldevice 2 in the gap period which is configured for use in ordinarymeasurement, it is possible to perform communication in the serving cellregardless of the switching timing at the terminal device 2.

Second Embodiment

Description will be given below for a second embodiment of the presentinvention. Though an example is shown in the first embodiment that a gapconfiguration for small-cell measurement is included in a measurementobject, an example is shown in the present embodiment that a parameterthat configures a time for identification of a small cell of a differentfrequency (Tidentify_inter_smallcell for small-cell identification) to ameasurement object by using a conventional gap configuration.

Since communication system (a base station device 1 and a terminaldevice 2) used in the description of the present embodiment is same asthat of FIG. 1 and FIG. 2 in the first embodiment, detailed descriptionthereof will not be repeated.

Subsequently, description will be given for a measurement configurationin the present embodiment by using FIG. 11.

In the same manner as the conventional RRM measurement configurationdescribed above, the measurement configuration in the present embodimentis configured by a measurement ID, a measurement object, a measurementobject ID corresponding to the measurement object, a reportconfiguration including a measurement event, and a report configurationID corresponding to the report configuration. Further, it is defined inthe present embodiment so that a configuration of the measurement objectis able to include a parameter for a small-cell identification timeconfiguration.

An example in which two measurement objects are defined as themeasurement configuration is shown in FIG. 11. The measurementconfiguration includes report configurations in addition the measurementobjects, and a measurement ID is configured to a combination of theaforementioned measurement object and report configuration.

In FIG. 11, a combination of a measurement object (frequency F2) of anidentifier 0 and a report configuration 1 of an identifier 0 isspecified as a measurement ID #0. In the same manner, a combination of ameasurement object (frequency F3, small-cell identification timeconfiguration) of an identifier 1 and a report configuration 2 of anidentifier 1 is specified as a measurement ID #1. Moreover, it is sethere that the event A1 described above is specified as the measurementevent for the report configuration 1 and the event A3 described above isspecified as the measurement event for the report configuration 2.

Next, description will be given for the measurement portion 204 in thepresent embodiment by using FIG. 12.

The measurement portion 204 includes an RRC layer reference signalmeasurement portion 1201 and a PHY layer reference signal measurementportion 1202. The PHY layer reference signal measurement portion 1202measures RSRP and RSRQ of a reference signal input from the receptionportion 201, a channel state and the like to notify the RRC layerreference signal measurement portion 1201. The RRC layer referencesignal measurement portion 1201 averages, if necessary, individualmeasurement results notified from the PHY layer reference signalmeasurement portion 1202 for the measurement object which is configuredby the measurement configuration notified from the higher layer 210 toconsider whether or not to be matched with the report configuration, andnotifies the measurement result to the higher layer 210. Here, when themeasurement object of the measurement configuration notified from thehigher layer 210 includes a parameter for a small-cell identificationtime configuration, the measurement portion 204 considers that thismeasurement object is the configuration for small-cell measurement.

Here, the terminal device 2, when the parameter for a small-cellidentification time configuration is included in the measurement objectof the measurement configuration message notified from the base stationdevice 1 in the same manner as the first embodiment, may consider thatthis measurement object is the configuration for small-cell measurement,and when information of one bit indicating small-cell measurement isincluded in the measurement object, consider that this measurementobject is the configuration for small-cell measurement. Alternatively,information of two bits or more may be included in the measurementobject to show that this measurement object is the configuration forsmall-cell measurement, a configuration for ordinary measurement, or aconfiguration for taking both of small-cell measurement and ordinarymeasurement.

Moreover, the parameter for a small-cell identification timeconfiguration is a parameter for calculating time which is configured toidentify a small cell, and, for example, may be time specificationitself to identify a small cell, may be bit information indicatingwhether or not time which is notified or prescribed in advance toidentify a small cell is applied to the corresponding measurementobject, or may be notification of a coefficient m when time foridentifying a small cell is time which is obtained by multiplying by aninteger number (m times) to a given unit time. Moreover, theaforementioned time for identifying a small cell may be configured so asto be a multiple of the number of frequencies (Nfreq) of the small cellto be measured as time for measuring one frequency.

Subsequently, description will be given for one example of measurementprocedure of the terminal device 2 in the communication system of thepresent embodiment by using a flowchart of FIG. 13.

In FIG. 13, first, the terminal device 2 receives a measurementconfiguration message from the base station device 1, and, based onwhether or not the parameter for a small-cell identification timeconfiguration described above is included in a measurement object,considers whether or not this measurement object is for use insmall-cell measurement (step S1301). When the measurement object is foruse in small-cell measurement (Yes at step S1301), a different frequencycell identification time is configured to a small-cell identificationtime (step S1302), and the flow shifts to step S1304. When themeasurement object is for use in ordinary measurement (No at stepS1301), the different frequency cell identification time is configuredto an identification time for use in ordinary measurement (step S1303),and the flow shifts to step S1304. At step S1304, the terminal device 2determines whether or not the aforementioned configuration is made forall measurement objects requiring a measurement gap configured to theown device, and when there is a measurement object to which theconfiguration is not made, the flow shifts to step S1301 to make aconfiguration of the different frequency cell identification time for anext measurement object. When the aforementioned configuration is madefor all the measurement objects requiring a measurement gap configuredto the own device at step S1304, the flow shifts to step S1305. Theterminal device 2 measures receiving power of a serving cell in whichthe own device is present and makes comparison with a threshold(s-Measure) at step S1305. When the receiving power of the serving cellis greater than or equal to the threshold (Yes at step S1305),measurement of the measurement object for use in small-cell measurementis carried out (step S1306). When the receiving power of the servingcell is less than the threshold (No at step S1305), measurement of themeasurement object for use in ordinary measurement is carried out (stepS1307).

Here, description will be given for operation of the terminal device 2when the small-cell identification time is applied as the differentfrequency cell identification time. For example, the identification timefor use in ordinary measurement is set as Tidentify_inter and thesmall-cell identification time is set as Tindentify_inter_smallcell.Here, when Tindentify_inter_smallcell is ten times of Tidentify_inter,the terminal device 2 is able to reduce frequency of different frequencymeasurement for identifying a small cell to one tenth of that ofordinary measurement. That is, even when the conventional gapconfiguration is applied to the terminal device 2, the terminal device 2is able to carry out it by classifying the frequency of small-cellmeasurement of a different frequency and the frequency of ordinarydifferent frequency measurement autonomously without clearly specifyinggap configuration for small-cell measurement like in the firstembodiment.

As described above, when the parameter for a small-cell identificationtime configuration is included in the configuration of the measurementobject and the terminal device 2 switches small-cell measurement andordinary measurement based on quality (receiving power) of the servingcell, it becomes possible to apply a different frequency cellidentification time suitable for each measurement and to search for adifferent frequency cell efficiently.

Further, measurement of the measurement object for use in small-cellmeasurement may not be performed not only when the receiving power ofthe serving cell is less than the threshold but when a mobility stateestimation value (MSE) of the terminal device 2 exceeds a threshold (forexample, in the case of middle speed or more or in the case of highspeed when the estimation value is represented by low speed, middlespeed or high speed). That is, when small-cell measurement itself is notperformed when the terminal device 2, even if being connected to a smallcell, falls out of the cell immediately (at the time of high-speedmovement), it becomes possible to search for a different frequency cellefficiently. The aforementioned threshold of the mobility stateestimation value may be configured individually for each measurementobject, or may be common in all the measurement objects for use insmall-cell measurement. In a case where the threshold is configured foreach measurement object, for example, when a cell size of a small cellis different for each frequency, etc., by setting the threshold as “highspeed” at the frequency with a large cell size and setting the thresholdas “middle speed” at the frequency with a small cell size, it becomespossible to search for a different frequency cell efficiently accordingto the cell size handled at each frequency.

Moreover, the parameter for a small-cell identification timeconfiguration may be changed according to the mobility state estimationvalue of the terminal device 2. For example, when the coefficient mdescribed above is used, scaling by the mobility state estimation valuemay be performed or the coefficient m (mHigh, mMid, mLow) may benotified for each mobility state estimation value (for example, for eachof high speed, middle speed and low speed). At this time, when m is 0,small-cell measurement for the corresponding measurement object may notbe performed. For example, by setting values of mHigh and mMid to 0, itis possible to cause only the terminal device 2 which moves at low speedto take small-cell measurement, so that it becomes possible to searchfor a different frequency cell efficiently.

In addition, when carrying out ordinary measurement, it is preferablethat a frequency of small-cell measurement is not included incalculation of Tidentify_inter or the like (that is, a frequency ofsmall-cell measurement is not included in Nfreq). Further, to thecontrary, when carrying out small-cell measurement, it is preferablethat a frequency of ordinary measurement is not included in calculationof Tidentify_inter_smallcell or the like (that is, a frequency ofordinary measurement is not included in Nfreq). Here, when measurementof the frequency of small-cell measurement is configured also toordinary measurement, this frequency is preferably included in Nfreq ofboth of them.

Note that, though an example is shown in the description above that ameasurement object for use in small-cell measurement is not measuredwhen the receiving power of the serving cell is less than s-Measure, themeasurement object for use in small-cell measurement may be measuredregardless of a value of s-Measure or even when s-Measure is notconfigured. In this case as well, since the base station device 1 stopssignal transmission to the terminal device 2 in the gap period which isconfigured for use in ordinary measurement, it is possible to performcommunication in the serving cell regardless of whether to be small-cellmeasurement or ordinary measurement.

Though examples have been shown in the first and second embodimentsdescribed above that a gap configuration for small-cell measurement andan identification time configuration are introduced, it is also possibleto apply both of them at the same time. That is, the base station device1 may notify the terminal device 2 of any of the gap configuration forsmall-cell measurement and the parameter for the small-cellidentification time configuration or both of them, and the terminaldevice 2 may apply time for identifying a small cell of a differentfrequency (Tindentify_inter_smallcell for small-cell identification) atthe time of measuring the measurement object to which the gapconfiguration for small-cell measurement is applied. When what isnotified from the base station device 1 to the terminal device 2 is anyof the gap configuration for small-cell measurement and the parameterfor the small-cell identification time configuration, for aconfiguration which is not notified, a given configuration for use insmall-cell measurement may be used or a configuration which is deriveduniquely from the notified configuration may be used.

Moreover, though description has been given in each embodiment describedabove regarding the parameter for small-cell identificationTidentify_inter, without limitation thereto, for example, also whenconfiguring a cell measurement time for RSRP or RSRQ measurement of asmall cell after cell identification (for example,Tmeasurement_period_inter_FDD or the like) or a small-cellidentification time using a different radio communication technology(for example, Tidentify, UTRA_FDD or the like), it may be set so that avalue becomes different depending on whether to be small-cellmeasurement or ordinary measurement.

Though an example is taken in each embodiment described above that thegap configuration for small-cell measurement or the parameter for thecell identification time configuration is included in a measurementobject, it may be included not in the measurement object but in ameasurement event. In this case, the gap configuration for small-cellmeasurement or the parameter for the cell identification timeconfiguration is to be applied to one or a plurality of measurementobjects which are associated with this measurement event.

Moreover, though description has been given in each embodiment describedabove that the gap configuration for small-cell measurement and/or thesmall-cell identification time configuration are/is switched betweenordinal measurement and small-cell measurement, a configuration forsmall-cell measurement may be changed to a configuration for an ordinaryconfiguration at the time of measuring receiving power (RSRP) orreception quality (RSRQ) after small-cell identification. For example,the terminal device 2 performs search of a small cell with low frequencybased on the gap configuration for small-cell measurement and/or thesmall-cell identification time configuration. When a cell is detected,based on the gap configuration for ordinary measurement and the cellmeasurement time configuration for ordinary measurement, the receivingpower or reception quality of the detected cell is measured and reportedto the base station device 1. In this manner, by switching theconfiguration for small-cell measurement to the configuration forordinary measurement after small-cell identification, it is possible tomeasure and report the receiving power and the reception qualitypromptly after small cell detection. At this time, the aforementionedconfiguration may be switched at a time when one cell is identified witha frequency of a measurement object or may be switched at a time whencells are identified by the number which is configured in advance.Further, when the receiving power or the reception quality of theidentified cell is less than a threshold which is configured in advance,a configuration which has been a configuration for ordinary measurementmay be returned to the configuration for small-cell measurement.

Moreover, a name of each parameter shown in the embodiments according tothe present invention is referred to for convenience of description, andeven when a parameter name which is applied actually is different from aparameter name of the present invention, a gist of the invention claimedby the present invention is not affected.

Though description has been given above in detail for one embodiment ofthis invention with reference to drawings, a specific configuration isnot limited to the above and various design change and the like can bemade without departing from the subject matter of this invention.

Moreover, the terminal device 2 of the embodiments described above isapplicable not only to a portable or movable mobile station device, butalso to stationary or unmovable electronic equipment which is installedindoors and outdoors such as, for example, AV equipment, kitchenequipment, cleaning/washing machine, air conditioning equipment, officeequipment, automatic vending machine, other domestic equipment,measurement equipment, an in-vehicle device, or the like. The terminaldevice is also referred to as a user terminal, a mobile station device,a communication terminal, a moving body, a terminal, UE (UserEquipment), or an MS (Mobile Station). The base station device is alsoreferred to as a radio base station device, a base station, a radio basestation, a fixed station, NB (Node-B), eNB (evolved Node-B) BTS (BaseTransceiver Station), or a BS (Base Station).

Further, though description has been given for the base station device 1and the terminal device 2 of the embodiments by using functional blockdiagrams for convenience of description, steps of a method or algorithmfor realizing functions or a part of these functions of each portion ofthe base station device 1 and the terminal device 2 may be embodieddirectly in hardware, in a software module executed by a processor, orin a combination of these two. If being implemented in software, thefunction may be held or transmitted as one or more commands or codes ona computer readable medium. The computer readable media include bothcommunication media and computer recording media including any mediumthat facilitates to transfer a computer program from one place toanother place.

Then, control of the base station device 1 and the terminal device 2 maybe performed by recording one or more commands or codes in a computerreadable recording medium and causing a computer system to read the oneor more commands or codes recorded in this recording medium forexecution. Note that, the “computer system” here is set to include an OSand hardware, such as peripheral equipment.

Operation described in each embodiment of the present invention may berealized by a program. The program which is operated at the base stationdevice 1 and the terminal device 2 related to each embodiment of thepresent invention is a program which controls a CPU or the like so as torealize the functions of the aforementioned embodiments involved in eachembodiment of the present invention (program causing a computer tofunction). In addition, information handled in these devices istemporarily accumulated in a RAM during processing thereof, and thenstored in various ROM or HDD to be read out by the CPU as necessary, forcorrection and writing. In addition, although the functions of theembodiments described above are realized by executing the program, thefunctions of each embodiment of the present invention are also realizedin some cases by performing processing based on instructions of theprogram in conjunction with an operating system or other applicationprograms.

Moreover, the “computer readable recording medium” refers to a portablemedium including a semiconductor medium (for example, such as RAM or anonvolatile memory card), an optical recording medium (for example, suchas a DVD, an MO, an MD, a CD or a BD), a magnetic recording medium (forexample, a magnetic tape or a flexible disk), or a storage deviceincluding a disc unit embedded in a computer system. Further, the“computer readable recording medium” includes one which dynamicallyholds a program for a short time, such as a communication line in a casewhere the program is transmitted through a network such as the Internetor a communication line such as a telephone line, and one which holds aprogram for a fixed time, such as a volatile memory inside a computersystem serving as a server or a client in the above case.

Moreover, the aforementioned program may be one for realizing a part ofthe functions described above, and further may be one capable ofrealizing the functions described above by being combined with a programwhich has been already recorded in a computer system.

Moreover, each functional block or various features of the base stationdevice 1 and the terminal device 2 used in each of the aforementionedembodiments may be implemented or executed by a general-purposeprocessor, a digital signal processor (DSP), an application specific orgeneral application integrated circuit (ASIC), a field programmable gatearray signal (FPGA), or other programmable logic devices, discrete gatesor transistor logic, or a discrete hardware component, which is designedto execute the functions described in the present specification, or acombination thereof. The general-purpose processor may be amicroprocessor, or alternatively, the processor may be a conventionalprocessor, a controller, a microcontroller or a state machine. Thegeneral-purpose processor or each circuit described above may beconfigured by a digital circuit or may be configured by an analoguecircuit.

The processor may be implemented also as a combination with a computingdevice. For example, a DSP and a microprocessor, a plurality ofmicroprocessors, a one or more microprocessors connected to a DSP core,or other such configuration are combined. Further, when a technology ofmaking into an integrated circuit superseding the LSI appears due toadvancement of a semiconductor technology, the integrated circuit bythis technology is also able to be used.

As above, the embodiments of the present invention have been describedin detail based on particular specific examples, however, it is clearthat a gist and a scope of Claims of the present invention are notlimited to these particular specific examples. That is, the descriptionin the present specification aims to give exemplary description and doesnot give any limitation to the present invention.

INDUSTRIAL APPLICABILITY

The present invention is applicable to a mobile phone, a personalcomputer, a tablet computer or the like.

DESCRIPTION OF REFERENCE NUMERALS

-   -   1 base station device    -   2 terminal device    -   101, 201 reception portion    -   102, 202 demodulation portion    -   103, 203 decoding portion    -   104, 205 control portion    -   105, 207 coding portion    -   106, 208 modulation portion    -   107, 209 transmission portion    -   108 neatwork signal transmission and reception portion    -   109, 210 higher layer    -   204 measurement portion    -   206 random access processing portion    -   61, 1201 RRC layer reference signal measurement portion    -   62, 1202 PHY layer reference signal measurement portion

The invention claimed is:
 1. A terminal device comprising: a receiverconfigured to, programmed to, or configured and programmed to receive ameasurement configuration which includes measurement object information,first information, and scaling factor information, the measurementobject information indicating a frequency to be monitored, the firstinformation indicating whether the frequency indicated by themeasurement object information is configured for a first measurement orfor a second measurement, and the scaling factor information being usedto scale a cell identification time of a measurement, wherein a cellidentification time of the first measurement being in proportion to anumber of frequencies to be monitored with the first measurement, and acell identification time of the second measurement is configured basedon the scaling factor information and the cell identification time ofthe second measurement being in proportion to a number of frequencies tobe monitored with the second measurement.
 2. A base station devicecomprising: a transmitter configured to, programmed to, or configuredand programmed to transmit a measurement configuration which includesmeasurement object information, first information, and scaling factorinformation, the measurement object information indicating a frequencyto be monitored, the first information indicating whether the frequencyindicated by the measurement object information is configured for afirst measurement or for a second measurement, and the scaling factorinformation being used to scale a cell identification time of ameasurement, wherein a cell identification time of the first measurementbeing in proportion to a number of frequencies to be monitored with thefirst measurement, and a cell identification time of the secondmeasurement is configured based on the scaling factor information andthe cell identification time of the second measurement being inproportion to a number of frequencies to be monitored with the secondmeasurement.
 3. A radio communication method applied to a terminaldevice comprising: receiving a measurement configuration which includesmeasurement object information, first information, and scaling factorinformation, the measurement object information indicating a frequencyto be monitored, the first information indicating whether the frequencyindicated by the measurement object information is configured for afirst measurement or for a second measurement, and the scaling factorinformation being used to scale a cell identification time of ameasurement, wherein a cell identification time of the first measurementbeing in proportion to a number of frequencies to be monitored with thefirst measurement, and a cell identification time of the secondmeasurement is configured based on the scaling factor information andthe cell identification time of the second measurement being inproportion to a number of frequencies to be monitored with the secondmeasurement.
 4. A radio communication method applied to a base stationcomprising: transmitting a measurement configuration which includesmeasurement object information, first information, and scaling factorinformation, the measurement object information indicating a frequencyto be monitored, the first information indicating whether the frequencyindicated by the measurement object information is configured for afirst measurement or for a second measurement, and the scaling factorinformation being used to scale a cell identification time of ameasurement, wherein a cell identification time of the first measurementbeing in proportion to a number of frequencies to be monitored with thefirst measurement, and a cell identification time of the secondmeasurement is configured based on the scaling factor information andthe cell identification time of the second measurement being inproportion to a number of frequencies to be monitored with the secondmeasurement.